Compact High—Power Blue Light from a Diode—Pumped Intracavity—Doubled Nd：YAG Laser

We report an efficient continuous wave(cw) operationof 946nm and 473nm laser beams generated from a diodepumped composte Nd:YAG rod.A very simple compact linear cavity was employed with cavity length of 35mm.A composite Nd:YAG laser rod was used to release thermal effects.The maximum cw output of 3.3W at 946nm was obtained with slope efficiency of 22% at incident pump power of 17.5W.By intracavity doubling with an LBO crystal,as much as 590mW of single-ended blue output at 473nm was achieved with an optical-optical conversion efficiency of 3.4%.The total blue output would be 1.06W with overall conversion efficiency of 6.1% if the lasers emitted in both the directions were taken into account.     

Highly efficient Nd:YAG/LBO laser at 473 nm under direct 885-nm diode laser pumping

<正>In diode pumped Nd:YAG lasers,the quantum defect is the most important parameter determining the thermal load of the laser crystal,which can be dramatically reduced by pumping directly into the upper laser level.A compact folded three-mirror cavity with a length of 105 mm is optimized to obtain a highly efficient 473-nm laser.When the absorbed pump power(with 15.8-W incident pump power) at 885 nm into Nd:YAG is 10 W,a continuous-wave 473-nm blue laser as high as 2.34 W is achieved by LBO intra-cavity frequency doubled.The optical-to-optical conversion efficiency is 14.8%.To the best of our knowledge, this is the highest efficiency at 473 nm by an intra-cavity doubled frequency Nd:YAG laser.     

Characteristics of Nd：GdVO4 Laser with Different Nd-Doping Concentrations

We report the properties of a compact diode-pumped continuous-wave Nd：GdV04 laser with a linear cavity and different Nd-doped laser crystals. In a 0.2at.% Nd-doped Nd：GdVO4 laser, 1.54 W output laser power is achieved at 912nm wavelength with a slope efficiency of 24.8% at an absorbed pump power of 9.4W. With 0.3at.% Nd-doping concentration, we can obtain the either single-wavelength emission at 1064nm or 912nm or the dual-wavelength emission at 1064nm and 912nm by controlling the incident pump power. From an incident pump power of 11.6 W, the 1064nm emission between ^4Fa/2 and ^4I11/2 is suppressed completely by the 912nm emission between ^4Fa/2 and ^4I9/2. We obtain 670 mW output of the 912nm single-wavelength laser emission with a slope efficiency of 5.5% by taking an incident pump power of 18.4 W. Using a Nd：GdV04 laser with 0.4at.% Nd-doping concentration, we obtain either the single-wavelength emission at 1064nm or the dual-wavelength emission at both 1064nm and 912nm by increasing the incident pump power. We observe a strong competition process in the dualavelength laser.     

All-Solid-State Nd:YAG Laser Operating at 1064nm and 1319nm under 885nm Thermally Boosted Pumping

We report a high-effciency Nd：YAG laser operating at 1064 nm and 1319nm, respectively, thermally boosted pumped by an all-solid-state Q-switched Ti：sapphire laser at 885 nm. The maximum outputs of 825.4 m W and 459.4mW, at 1064nm and 1319nm respectively, are obtained in a 8-ram-thick 1.1 at.% Nd：YAG crystal with 2.1 W of incident pump power at 885nm, leading to a high slope efficiency with respect to the absorbed pump power of 68.5% and 42.0%. Comparative results obtained by the traditional pumping at 808nm are presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power at 1064nm under the 885nm pumping are 12.2% higher and 7.3% lower than those of 808rim pumping. At 1319nm, the slope efficiency and the threshold with respect to the absorbed pump power under 885nm pumping are 9.9% higher and 3.5% lower than those of 808 nm pumping. The heat generation operating at 1064 nm and 1319 nm is reduced by 19.8% and 11.1%, respectively.     

High Power Diode-End-Pumped Nd：YAG 946-nm Laser and Its Efficient Frequency Doubling

We report a high power operation of the ^4Fa/2 → ^4I9/2 transition in diode-end-pumped laser at 946nm. The maximum output of 5.1 W is obtained with a short linear plano-concave cavity, and the slope efficiency is 24.5% at incident pump power of 23.3 W. To our knowledge, this is the highest value of the LD-pumped Nd:YAG 946 nm lasers that employ the conversional Nd:YAG rod as the gain medium. By intracavity frequency doubling with an LBO crystal, up to 982mW cw output power in the blue spectral range at 473nm is achieved at an incident pump power of 10.9 W with a compact three-element cavity, leading to optical-to-optical conversion efficiency of 9%. The conversion efficiency should be increased to 15.1%, if the rather low absorption coefficient of this Nd:YAG is considered.     

All-Solid-State Near-Infrared and Blue Femtosecond Laser System

We investigate an all-solid-state continuous wave(cw) green (532nm),femtosecond near-infrared (823.1nm) and blue (402nm) laser system which is pumped by a diode-laser-pumped intracavity frequency-doubled and all-self-structuring cw Nd:YVO4/KTP 532nm green laser.The cavity parameters of the Nd:YVO4/KTP laser have been optimized and the maximum 5.6W TEM00 green laser is obtained at a 22W pump power with an optical-optical conversion efficiency of 25.5%.A Ti:Sapphire laser and nonlinear second-harmonic generation by a crystal BBO is used to obtain different wavelengths.A femtosecond laser with an average output power of 300mW at 823.1nm and 73mW at 402nm is obtained when the green pump power is 2.5W.The spectral full width at half maximum are 32.3 nm and 5.1 nm,which can sustain the pulses of 22 fs and 33.3 fs,respectively.     

1 kHz nanosecond-pulsed room temperature Fe:ZnSe laser gain-switched by a ZnGeP_2 optical parametric oscillator

We demonstrate a Fe:ZnSe laser gain-switched by a ZnGeP_2 optical parametric oscillator(OPO) under the pulse repetition frequency of 1 kHz at room temperature. The 2.9 μm signal light of the OPO is employed as the pump for the Fe:ZnSe laser. The maximum output power of the Fe:ZnSe laser is 58 mW with the pulse duration of 2.7 ns under the incident pump power of 280 mW, corresponding to a peak pulse power of 21.5 kW and an optical-to-optical efficiency of 20.7%. The spectrum of the Fe:ZnSe laser has a range of 4030.2–4593.6 nm with a dip at 4187.1–4340.4 nm due to the absorption of CO_2.     

Efficient Tm：YAG Ceramic Laser at 2 μm

We demonstrate a high-efficiency continuous-wave Tm： YAG ceramic laser pumped with a Ti：sapphire laser. An output power up to 860mW is obtained under an absorbed pump power of 2.21 W at 785nm, corresponding to a slope efficiency of 42.1% and optical to optical efficiency of 22%. The measured central wavelength is 2012nm.     

Diode Pumped Operation of Tm,Ho：YVO4 Microchip Laser

A cryogenic and room-temperature diode pumped Tm,Ho：YVO4 microchip laser with 0.5 mm crystal length lasing around 2μm is demonstrated for the first time to our knowledge. Under cryogenic temperature of 77 K, as much as 1.2 W output and slope efficiency of 35% with respect to absorbed pump power are obtained. At temperature of 5℃ the maximum output power of 48mW is obtained at an absorbed pump power of 503 mW, representing a 9.5% optical to optical conversion efficiency. In addition, as much as 8 mW single-frequency output lasing at 2052.6 nm is achieved at room temperature of 15℃.     

Acousto-optic Q-switched laser performances of Er3+:Yb3+:LuAl3（BO3）4 crystal at 1.5-1.6 μm

Diode-pumped acousto-optic Q-switched pulse laser at 1.5-1.6 μm is obtained in an Er3+:Yb3+:LuAl3 (BO3)4 crystal. Single-pulse laser operation with slope efficiency of 14% and threshold of approximately 100 mW is realized at an average absorbed pump power of 314 mW and repetition frequency of 20 kHz. Output pulse energy is 67 μJ. The effects of pulse repetition frequency, absorbed pump power, and duty cycle on the wavelength and pulse profile of the Q-switched Er3+:Yb3+:LuAl3(BO3)4 laser are also investigated.     

Mid—Infrared Optical Parametric Oscillator Based on All—Solid—State—Pumped Periodically Poled LiNbO

We report the tunable mid-infrared generation with a periodically poled LinbO3(PPLN).Using an all-solid-state pumped Nd:YVO4 laser as the pump source and a PPLN nonlinear crystal with grating periods of 28.2-30.8μm,we have achieved wavelength conversion in the 2.90-4.05μm spectral range by period tuning.The use of confocal cavity design has brought a compact,all-solid-state configuration with an average output powers of idler up to -200mW.The maximum power of 277mW was obtained at the wavelength of 3.35um.     

Diode-pumped high-efficiency broadband tunable Tm:YAP laser

A laser diode-pumped high-efficiency widely tunable Tm:YAP laser with excellent comprehensive properties is reported.The output power is stable at a given pump power.Under the absorbed pump power of 12.95 W,the maximum output power at 2,010 nm is 5.16 W,corresponding to a slope efficiency of 45.5%.The generated beam profile is close to the Gaussian TEM00 near the maximum pump power.Furthermore,the laser working wavelength can be continuously tuned through optimization from 1,894 to 2,066 nm,which is the widest tunable range for Tm:YAP lasers to date.     

Laser Characteristics of Cladding-Pumped Short Er^3＋/yb^3＋ Codoped Single Mode Phosphate Glass Fibre

We experimentally investigate the laser characteristics of a series of short pieces of newly-developed Er^3＋/ Yb^3＋ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85 m W at 1553nm is generated from a 5.5-em-long active fibre. Single mode laser output power per unit length is up to 15 mW/cm. Moreover, the slope efficiency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.     

A Novel Conventional／Long—Band Erbium—Doped Fibre Amplified Spontaneous Emission Source with 80 nm Bandwidth

We report on a one-stage erbium-doped fibre amplified spontaneous emission (ASE) source with 80 nm bandwidth and 13.5 dBm output power.the broad bandwidth erbium ASE source was realized in an erbium-doped fibre with 37m length by a 1480 nm laser diode and a 980 nm laser diode as forward and backward pump sources,respectively.The total pump power is only 95.7mW.     

Diode-pumped Nd:Y_xGd_(1-x)VO_4 crystal continuous-wave laser

The diode-pumped Nd:YxGd1-xVO4 crystal continuous wave (CW) laser operating at 1.06 μm with a simple plane-concave cavity and a "V-shaped" folded cavity for intracavity frequency-doubling have been studied. With the incident pump power of 8 W, an output power (1.06μm) of 3.4 W was achieved, giving an optical conversion efficiency of 42.5%. 884 mW of stable green radiation was generated with the incident pump power of 5.9 W, giving an optical conversion efficiency of 15%.     

All-solid-state quasi-continuous-wave high power dispersion cavity tunable Ti:sapphire laser

An all-solid-state quasi-continuous-wave dispersion cavity tunable Ti:sapphire laser pumped by a laser diode pumped frequency-doubled Nd:YAG laser is reported. Using a dense flint glass prism as the dispersion element, a tuning range from 730 to 880 nm with the linewidth of 3 nm and the pulse width of 17.2ns was obtained. The maximum output power of this laser system was 5.6 W at 786.3 nm corresponding to an optical-to-optical conversion efficiency of 25.5% under the pump power of 22 W.     

All-solid-state quasi-continuous-wave high power dispersion cavity tunable Ti:sapphire laser

An all-solid-state quasi-continuous-wave dispersion cavity tunable Ti:sapphire laser pumped by a laser diode pumped frequency-doubled Nd:YAG laser is reported. Using a dense flint glass prism as the dispersion element, a tuning range from 730 to 880 nm with the linewidth of 3 nm and the pulse width of 17.2 ns was obtained. The maximum output, power of this laser system was 5.6 W at 786.3 nm corresponding to an optical-to-optical conversion efficiency of 25.5% under the pump power of 22 W.     

Watt-level Pr~(3+):YLF deep red laser pumped by a fiber-coupled blue LD module or a single-emitter blue LD

A power-scaled laser operation of Pr:YLi F4(YLF)crystal at 720.9 nm pumped by a 443.6 nm laser diode(LD)module was demonstrated.The 20 W module was used to pump the Pr:YLF crystal,and a maximum output power of 3.03 W with slope efficiency of 30.04%was obtained.In addition,a 5 W blue LD was also used to pump the Pr:YLF laser,and a maximum output power of 0.72 W was obtained at room temperature.The output power was limited by the wavelength mismatch between the single-emitter LD and the absorption peak of the crystal.     

Compression of the self-Q-switching in semiconductor disk lasers with single-layer graphene saturable absorbers

We demonstrate the first use of single layer graphene for compressing self-Q-switching pulses in semiconductor disk lasers. The gain region of the semiconductor disk laser used InGaAs quantum wells with a central wavelength of 1030 nm. Due to self saturable absorption of the quantum wells, the disk laser emitted at the self-Q-switching state with a pulse width of 13 μs. By introducing the single layer graphene as a saturable absorber into the V-shaped laser cavity, the pulse width of the self-pulse was compressed to 2 μs with a lower pump power of 300 mW. As the pump power was increased, multiple pulses with the pulse width of 1.8 μs appeared. The compression factor was about 7.2.     

Q-switched Er-doped fiber laser with low pumping threshold using graphene saturable absorber

We propose a Q-switched Er-doped fiber laser(EDFL) with a threshold pumping power as low as 7.4 mW, and demonstrate using graphene polyvinyl alcohol(PVA) thin film as a passive saturable absorber(SA). The SA is fabricated from graphene flakes, which is synthesized by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulfate aqueous solution. The flakes are mixed with PVA solution to produce a thin film, which is then sandwiched between two ferrules to form a SA and integrated in the EDFL ring cavity to generate a stable Q-switched pulse train. The pulse train operates at 1560 nm with a threshold pump power of 7.4 mW. At maximum 1480 nm pump power of 33.0 mW, the EDFL generates an optical pulse train with a repetition rate of 27.0 kHz and pulse width of 3.56 μs. The maximum pulse energy of 39.4 nJ is obtained at a pump power of 14.9 mW. This laser can be used as a simple and low-cost light source for metrology, environmental sensing, and biomedical diagnostics.